Turbines used in the electrical power generation industry typically include a plurality of combustors which are arranged concentrically around the exterior of the compressor section of the turbine. Within each combustor, a plurality of fuel nozzles are typically mounted on a combustor cap that is located near the upstream end of the combustor. Compressed air flows through and past the nozzles to reach a combustion zone within the combustor. As the air travels through and past the fuel nozzles, fuel is injected into the airflow, and the air and the fuel mix together to produce a fuel-air mixture which is ignited in the combustion zone of the combustor.
In many combustors, one fuel nozzle will be located at the center of the combustor cap, and a plurality of nozzles will be arranged around the exterior of the center nozzle in a symmetric fashion.
During some operational conditions, only a subset of all of the available fuel nozzles will be delivering fuel into the flow of air. For instance, in some operational conditions, fuel will only be delivered through the center fuel nozzle. In other instances, fuel may be delivered through the center fuel nozzle and a subset of the fuel nozzles surrounding the center nozzle.
In some combustors, when immediately adjacent fuel nozzles are both delivering fuel into the flow of air, the combusting flow of fuel and air interacts to produce an audible noise. The generation of the audible noise by itself is undesirable. However, the vibrations that generate the noise can also be physically damaging to the combustor over an extended period of time. Accordingly, the generation of such audible noise is undesirable.
Such noise generation may occur, for example, when the nozzles are burning high hydrogen content fuel. The burning of high hydrogen can result in combustion dynamic tones at higher than 1 kHz.